The present invention relates to contact lens packages, and in particular to disposable contact lens packages commonly referred to as blister packages.
Soft hydrogel contact lenses have been increasing in popularity ever since they were first introduced in the 1970's. Such contact lenses are conventionally packaged in the hydrated state and in a storage solution. Currently, many contact lenses are packaged, along with the aqueous storage solution, in a disposable plastic blister package. Examples of blister packages can be seen in U.S. Pat. Nos. 4,691,820; 5,524,419; 5,578,331, 5,649,410 and 5,722,536, the entire disclosures of which are incorporated herein by reference. The base of a blister package can either be part of the original contact lens mold or a separately molded base. Examples of packages using the mold as part of the package can be seen in U.S. Pat. Nos. 5,036,971; 5,143,660; 5,407,062 and 5,573,108, the entire disclosures of which are incorporated herein by reference. In all of the above mentioned package types, the base that contains the contact lens and any aqueous storage solution, whether it is a separated molded base or part of the original contact lens mold, is sealed by a flexible lidstock. This lidstock is typically a laminated foil which can be pulled back by a user to access the lens contained in the base. Typically, this lidstock is sealed to the area surrounding the portion of the base containing the contact lens. This sealing area of the base has typically been a flat surface area, or a raised flattened annular surface as seen, for example, in U.S. Pat. No. 5,722,536. However, it has been found that this flat surface, whether raised or not, can pose problems during the sealing process. If a molding s process is used to form the blister package, for example, the material may have some shrinkage, resulting in somewhat concave sealing surface. Any low spots or unevenness of the sealing surface can additionally cause microbubbles and result in a poor seal. Storage solution used to keep the contact lens hydrated can inadvertently spill and then remain on the sealing area; this can lead to a poor seal between the lidstock and the package base.
Accordingly, it is an object of the present invention to provide a package for contact lenses that includes an improved sealing area on the base of contact lens package.